The invention relates to a single-use test element for examining a body fluid, comprising a lancing member that can prick a body part, a collecting area configured thereon for collecting body fluid obtained by the lancing, and at least one light guide for an optical measurement in the collecting area. The invention also relates to a test system for the use of such test elements.
In the case of blood sugar self-monitoring that is carried out several times daily as part of an insulin treatment, it is desirable to impose as few as possible handling steps on the affected person and, at the same time, to ensure a painless and reliable measurement. For reasons of hygiene, single-use articles are used for this monitoring, which, as a mass-produced article, should be produced as cheaply as possible. The conventional concepts envisage transport of blood fluid, which is usually removed from the finger tissue area by a lancet puncture, onto a separate sensory element, for example, in the form of a test strip, in order to then start the actual measurement.
In order to further integrate the system, a combined arrangement was proposed in DE 10 325 699 in which a light-conducting hollow fiber is arranged concentrically around a coaxially movable lancet. The hollow fiber has a reagent layer on a distal front end which is loaded with escaping blood when the lancet is inserted into the body part, while light from an analytical unit can be coupled into or out of the proximal end of the hollow fiber. In a complementary design, the system has a hollow cannula with a light guide that can be moved therein whose distal end that is arranged in the cannula opening is also coated with an analyte-specific reagent. In order to simplify the sampling, the end of the light guide is pushed out of the cannula opening after the lancing process until it protrudes beyond the opening and thus ensures a problem-free contact of the test field with the blood of the patient. However, an additional drive control is necessary for the relative movement of the lancing element and light guiding element, and a check whether the blood contact has been successful is not envisaged.